September 25, 2013:
Note that I am not speaking to the covenant of marriage in my thoughts below.
Are all relationships ordained to last forever? I don't believe so. God brings people in and out of our lives in His perfect timing for a host of reasons, and not all of these ties are necessarily open-ended. We obey, sow as He leads, and hopefully receive a deposit in return. Notwithstanding the fact that healthy relationships are forged when they are mutual, but often things just come to a close. God will put that knowing in your heart that He's getting ready to close a door. But He will also ready your heart as He points you toward the new doors that hold new relationships, which are very much a part of what is necessary in your destiny, as well as others.
Instead of pushing back or refusing to let go, get quiet and ask for His perspective and peace in moving forward toward this unknown. If God is in it, it's going to be good.